In most of UAV applications it is essential to determine the exterior orientation of on-board sensors and precise ground locations of images acquired by them. This paper presents a precise methodology for 3D geo-location of UAV images using geo-referenced data. The fundamental concept behind this geo-location process is using database matching technique for refining the coarse initial attitude and position parameters of the camera derived from the navigation data. These refined exterior

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... ion parameters are then used for geo-locating entire image frame using rigorous collinearity model in a backward scheme. A forwards geo-locating procedure also is proposed based on a ray-DSM intersection method for the cases where ground location of specific image targets (and not the entire frame) is required. Experimental results demonstrated the potential of the proposed method in accurate geo-location of UAV images. Applying this method, an RMSE of about 14 m in horizontal and 3D positions has been obtained.